Many optical applications require small and highly efficient optical light sources. Cholesteric LCs show an intrinsic periodic helical structure, which can replace a laser resonator. Dr. Jürgen Schmidtke works very successfully on fabricating and characterizing tunable lasers based on polymer and low molar mass cholesteric LCs. Other classes of LCs, smectic and columnar liquid crystals, can act as organic semiconductors with an unusually high charge carrier mobility. Their electroluminescent application requires sophisticated nanostructures composed ultrathin multilayers. Unlike luminescent polymers, LCs are capable of emitting polarized light. Their performance can be enhanced by embedding in a microresonator.